Method of producing titanium



' March 11, 1958 F w. GARRETT EI'AL 2,826,493

METHOD OF PRODUCING TITANIUM Filed March 28, 1955 Drain INVENTORS FREDERICK W. GARRETT ROBERT A.SKIM|N BY ORNEY 7" States 2,826,493 Patented Mar. 11, 1958 METHOD OF PRODUCING TITANIUM Frederick W. Garrett, Niagara Falls, Ontario, Canada, and Robert A. Skimin, Niagara Falls, N. Y., assignors to Union Carbide Corporation, a corporation of New York This invention relates to a method of producing reactive metals of groups IV, V and VI of the periodic table. More particularly the invention relates to a process for producing titanium metal.

Production of the metals'of groups IV, V and VI of the periodic table has long presented severe difiiculties. The most promising methods have been based on the reduction of a halide of the metal by one of the alkali metals. Although many procedures have been suggested for carrying out the basic reaction, and some have been employed on a semi-commercial scale, none of the pro cedures is without operational difficulties or hazards. The reduction reaction is exothermic in character and therefore the reactants must be brought together under carefully controlled conditions to achieve satisfactory results. Among the difliculties encountered with prior art techniques for the manufacture of metals like titanium is that of minimizing vaporization of the reactants. Vapor phase reactions lead to the deposition of products on nozzles and other parts of the equipment which makes control of the reaction and product removal more difiicult. Agitation of the reactants is complicated by the formation of solid products that interfere with the operation of mechanical agitators.

It is the object of this inventionto provide a method for producing reactive metals of groups IV, V and VI of the periodic table. it ,is a further object of this invention to I provide a successful method for producing such metals of high purity. Still another object is to provide a process for the productionof titanium of high purity.

Broadly the objects of the invention are accomplished by the reduction in -two stages of a halide of the metal to be produced. In the first stage the halide is reduced to subhalides with a molten reducing metal. In the second stage the subhalides are reduced to the metallic state by the further addition of molten reducing metal in an amount sutficient to provide the stoichiometric amount of reducing metal required to react with the halide. An inert or non-contaminating atmosphere is maintained throughout the reduction. i

The subject invention provides a method for the production of the designated metals that overcomes in great measure the difliculties and hazards encountered heretofore. Additionally, segregation and localized heating are virtually eliminated, and improved utilization of the reactants is realized.

According to the method of the invention, the reduction reaction is carried out in two stages These stages may be performed with or without intermediate delay and may be carried out in the same or diiferent reactors. For example, in the production of titanium metal following the teachings of the invention, molten alkali metal and titsnium tetrachloride are placed in a reactor. The amount of alkali metal used in this stage is insufficient to reduce the titanium tetrachloride to titanium. The titanium tetra- 70 chloride is reduced to subchlorides of titanium while an alkali metal chloride is simultaneously formed. The subchlorides are subsequently reduced, producing titanium metal and additional quantities of alkali metal chloride, by injecting molten alkali metal into the bath of titanium subchlon'des and alkali metal chlorides. An inert or non-contaminating atmosphere, for example argon, is maintained throughout the reduction, and the alkali chloride and reactants are maintained in a molten state. Certain efficiencies in the use of equipment may be realized by conducting the initial reduction in one relatively large chamber and the subsequent reduction of the subchlorides of titanium in a series of smaller vessels. Some advantage is obtained in providing a small amount of the alkali metal halide in the reactor initially to provide ample solvent for the refractory titanium subhalide.

The accompanying drawing is a schematic representation of an apparatus whereby the objects of the invention may be achieved.

In the drawing:

A metallic reaction chamber 1 is provided in its upper portion with a feed line 2 terminating in a nozzle 3. In the lower portion of the chamber is a feed line for molten reducing metal 4 terminating in a nozzle 5. Alternatively the feed line 4 may extend from the top of the chamber in which event provision may be made to lower it into the reactants if desired. A drain line 6 is provided for withdrawing the molten chlorides.

As an example of the practice of the invention the reduction of titanium tetrachloride with sodium will be de scribed. The reactor 1 is purged of air and filled with a non-contaminating gas, for example, argon. The reactor 1 is then charged with a quantity of molten sodium throng-h feed line 4 and nozzle 5. The temperature is maintained at a level above the melting point of the sodium. Approximately twice the stoichiometric quantity of titanium tetrachloride is injected at high velocity into the bath of molten sodium through feed line 2 and nozzle 3. This procedure will produce a mixture of titanium subchlorides and sodium chloride; It is thought that the titanium subchloride formed is either substantially TiCl or other titanium subchlorides dissolved in the alkali metal chloride, or complexes of these subchlorides and the alkali metal chloride. In any event the fluidity of the bath is not reduced and the melting point of the mixture is below that of pure sodium chloride. 7

After the injection of the titanium tetrachloride is completed the remaining sodium, in a quantity sufficient to completely react with the chloride present in the reactor 1, is injected, for example, through a nozzle 5 immersed, for example, within the bath. The greater part of the resulting sodium chloride may then be drained from the reactor. Any remaining sodium chloride may be removed from the titanium metal formedin the reactor by conventional methods such as leaching or vacuum distillation.

It has been determined that the injection velocity of the refractory metal halide may be between about 0.1 and 200 feet per second, and of the molten alkali metal in the second stage of the reduction at a velocity of between about 0.1 and feet per second. Relatively high velocities are preferred since the agitation of the reactants is promoted thereby.

Typical reductions illustrative of the method of the invention are as follows: a

Example I About 97 pounds of sodium metal were charged in the liquid state to the reactor in an atmosphere of substantially pure argon. The metal bath was raisedto a temperature of approximately 400 C. About 416 pounds of titanium tetrachloride, approximately twice the quantity of titanium tetrachloride need to react stoichiometrically with the sodium metal to form titanium, were injected into the metal bath at a velocity of from 3 to 20 feet per second through a nozzle located in the lid of the reactor. During this injection period the temperature of the reacting bath slowly increases heating the reactor walls to approximately 850 C. After the feeding of the titanium tetrachloride was completed, 105 pounds of liquid sodium, the amount required to react stoichiometrically with the titanium compounds, were injected into the mixture. This injection was through a feed line located below the surface of the oath. The sodium traveled at a velocity of about 6 feet per second, and the temperature of the walls of the reactor was maintained between about 850 C. and 950 C. The contents of the reactor were then held at a temperature of between about 900 C. and 950 C. for two hours to permit the completion of the reactions. Much of the liquefied sodium chloride was drained leaving a mass of titanium sponge and some 'sodium chloride within the reactor. The remaining sodium chloride was removed by leaching. The titanium metal was found to have or ceptional purity, containing less than 0.15% oxygen, 0.03% nitrogen and 0.10% chlorine.

Example II Sodium metal in the amount of 6.86 pounds and sodium chloride in the amount of 17.5 pounds were heated in an argon-filled reaction chamber to 850 C. Titanium tetrachloride in the amount of 28 pounds was injected into the molten bath at a velocity of about 60 feet per second through a nozzle located in the lid of the chamber. After the feeding of the titanium tetrachloride was completed, 7 pounds of molten sodium metal were injected into the mixture of molten chlorides through a second sodium feed line located above the surface of the bath at a velocity of 125 feet persecond. Upon the separation of the sodium chloride from the titanium metal, the metal was found to be of good quality and high purity.

What is claimed is:

1. In the production of titanium metal by the alkali metal reduction of titanium tetrachloride, the improvement which comprises first reducing substantially all of the titanium tetrachloride to molten titanium subchloride by directing a'stream of titanium tetrachloride at high velocity into a bath of molten alkali metal at a rate and in amount in excess of that which the alkali metal can reduce to titanium so as to avoid the formation of titanium metal at this stage, and then injecting at high velocity into the thus formed molten titanium subchloride a further amount of molten alkali metal sufiicient to reduce the molten subchloride to the metallic state.

2. A process in accordance with the process of claim 1 wherein the injection of molten alkali metal into the molten titanium subchloride is effected below the surface of said moltentitanium subchloride.

3. In the production of titanium metalby the alkali metal reduction of titanium tetrachloride, the improvement which comprises first reducing substantially all of the titanium tetrachloride to molten titanium subchloride by directing a stream of titanium tetrachloride at high velocity into a bath of molten alkali metal at a rateiand in amount in excess of that which the alkali metal can reduce to titanium so as to avoid the formation of titanium metal at this stage, and then injecting at high velocity into the thus formed molten titanium subchloride a fur ther amount of molten alkali metal sufiicient to reduce the molten subchloride to the metallic state, said reductions being effected in a substantially non-contaminating atmosphere.

4. In the production of titanium metal by the sodium reduction of titanium tetrachloride, the improvement which comprises first reducing substantially all of the titanium tetrachloride to molten titanium subchloride by directing a stream of titanium tetrachloride at high velocity into a bath of molten sodium at a rate and in amount in excess of that which the sodium can reduce to titanium so as to avoid the formation of titanium metal at this stage, and then injecting at high velocity into the thus formed molten titanium subchloride a further amount of molten sodium sufficient to reduce the molten subchloride to the metallic state. a

5. A process in accordance with the process of claim 4 wherein the injection of molten sodium into the molten titanium subchloride is effected below the surface of said molten titanium subchloride.

6. In the production of titanium metal by the sodium reduction of titanium tetrachloride, the improvement which comprises first reducing substantially all of the titanium tetrachloride to molten titanium subchloride by directing a stream of titanium tetrachloride at high velocity into a bath of molten sodium at a rate and in amount in excess of that which the sodium can reduce to titanium so as to avoid the formation of titanium metal at this stage, and then injecting at high velocity into the thus formed molten titanium subchloride a further amount of molten sodium sufficient to reduce the I molten subchloride to the metallic state, said reductions being effected in a substantially non-contaminatingatmosphere.

7. In the production of titanium metal by the sodium reduction of titanium tetrachloride, the improvement which comprises first reducing substantially all of the titanium tetrachloride to molten titanium subchloride by directing a stream of titanium tetrachloride at high ve locity into a bath of molten sodium at a rate and in amount in excess of that which the sodium can reduce to titanium so as to avoid the formation of titanium metal at this'stage, and then injecting at high velocity into the thus formed molten titanium subchloride a further amount of molten sodium suflicient to reduce the molten subchloride to the metallic state, said reductions being effected in a substantially non-contaminating atmosphere and at a temperature not greater than 950 C.

References Cited in the file of this patent UNITED STATES PATENTS 2,148,345 Frudenber Feb. 21, 1939 2,443,253 Kroll et al. June 15, 1948 2,586,134 Winter Feb. 19, 1952 2,607,674 Winter Aug. 19, 1952 2,616,800 Wartman Nov. 4,1952 2,618,549 Glasser et a1. .4. Nov. 18, 1952 2,618,550 Hampel et a1 Nov. 18, 1952 2,647,826 Jordan Aug. 4, 1953 2,667,413 Jordan Jan. 26, 1954 2,703,752 Glasser et al Mar. 8, 1955 2,753,256 Olson July 3, 1956 FOREIGN PATENTS 694,921 Great Britain July 29, 1953 1,094,987 France Dec. 15, 1954 OTHER REFERENCES Zeitschrift fur Anorganische und Allegemeine Chemie, vol. 23 4, 1937, pages 42-50, pages 43, 44 pertinent. Metal Industry, May 16, 1947, pages 363-364. Journal of Metals, April 1950, pages 634-640. Aagaard: Abstract of appl. S. N. 129,305, filed Nov. 25, 1949. Published Aug. 14, 1951, 649 0.76. 604.

Chemical Engineering Progress, vol. 50, No. 11, November 1954, pages 578-581. 

1. IN THE PRODUCTION OF TITANIUM METAL BY THE ALKALI METAL REDUCTION OF TITANIUM TETRACHLORIDE, THE IMPROVEMENT WHICH COMPRISES FIRST REDUCING SUBSTANTIALLY ALL OF THE TITANIUM TETRACHLORIDE TO MOLTEN TITANIUM SUBCHLORIDE BY DIRECTING A STREAM OF TITANIUM TETRACHLORIDE AT HIGH VELOCITY INTO A BATH OF MOLTEN ALKALI METAL AT A RATE AND IN AMOUNT IN EXCESS OF THAT WHICH THE ALKALI METAL CAN REDUCE TO TITANIUM SO AS TO AVOID THE FORMATION OF TITANIUM METAL AT THIS STAGE, AND THE INJECTING AT HIGH VELOCITY INTO THE THUS FORMED MOLTEN TITANIUM SUBCHLORIDE A FURTHER AMOUNT OF MOLTEN ALKALI METAL 